Coal upgrading utilizing carbon dioxide

ABSTRACT

Coal is upgraded through use of carbon dioxide and/or nitrogen and optionally integrated with a combustion process.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims the benefit under 35 U.S.C. §119(e) toprovisional application No. 60/740,607, filed Nov. 29, 2005, the entirecontents of which are incorporated herein by reference.

BACKGROUND OF THE INVENTION

Coal, when mined, comes with lot of impurities. The process of coalupgrading at the mine has been practiced for a long time, mainly toremove the moisture and other easily removable impurities. It was foundthat steam and certain inert gases were used before for this process.This process is not practiced all the time because of unavailability ofthe ingredients and economical reasons.

BRIEF SUMMARY OF THE INVENTION

The present invention proposes an innovative process to upgrade/cleancoal prior to its use. Upgrading the coal refers to reducing variousimpurities that are present in mined or raw coal to make the coalcleaner, and also to increase the energy content per unit weight of thecoal. The proposed process cleans or upgrades the coal using CarbonDioxide (CO2), and/or Nitrogen (N2), depending on the impuritiestargeted and the intended purpose. Combusting upgraded coal results inlower environmental pollutant emissions and increased combustionefficiency. Some coals that cannot be combusted in raw condition can bemade possible to combust with the proposed upgrading process.

Purifying the flue gas obtained from combustion of coal is often veryexpensive. Any effort to purify the coal prior to the combustion canresult in significant savings. Also, some lower rank coals that cannotbe combusted in typical/traditional combustors can be made possible tocombust with the proposed upgrading process.

BRIEF DESCRIPTION OF THE DRAWINGS

For a further understanding of the nature and objects of the presentinvention, reference should be made to the following detaileddescription, taken in conjunction with the accompanying drawings, inwhich like elements are given the same or analogous reference numbersand wherein:

FIG. 1 is a schematic of an integrated process for upgrading coal usingcarbon dioxide and nitrogen;

FIG. 2 is a schematic of the process of FIG. 1 utilizing a carbondioxide cleaning unit;

FIG. 3 is a schematic of the process of FIG. 1 utilizing a nitrogencleaning unit;

FIG. 4 is a schematic of the process of FIG. 1 utilizing carbon dioxideand nitrogen cleaning units;

FIG. 5 is a schematic of the process of FIG. 1 utilizing flue gasrecycling;

FIG. 6 is a schematic of the process of FIG. 1 utilizing a carbondioxide cleaning unit and flue gas recycling;

FIG. 7 is a schematic of the process of FIG. 1 utilizing a nitrogencleaning unit and flue gas recycling;

FIG. 8 is a schematic of the process of FIG. 1 utilizing a carbondioxide cleaning unit, a nitrogen cleaning unit, and flue gas recycling;

FIG. 9 is a schematic of a process for upgrading coal using coal carbondioxide;

FIG. 10 is a schematic of the process of FIG. 9 utilizing a carbondioxide cleaning unit;

FIG. 11 is a schematic of the process of FIG. 9 utilizing combustionwith coal to produce the carbon dioxide;

FIG. 12 is a schematic of the process of FIG. 11 utilizing a carbondioxide cleaning unit;

FIG. 13 is a schematic of the process of FIG. 9 utilizing flue gasrecycling;

FIG. 14 is a schematic of the process of FIG. 13 utilizing a carbondioxide cleaning unit;

FIG. 15 is a schematic of a process for upgrading coal with nitrogen;

FIG. 16 is a schematic of the process of FIG. 15 utilizing a nitrogencleaning unit;

FIG. 17 is a schematic of the process of FIG. 15 utilizing an airseparation unit to produce the nitrogen; and

FIG. 18 is a schematic of the process of FIG. 17 utilizing a nitrogencleaning unit.

DETAILED DESCRIPTION

The present process and system propose the integrated use of carbondioxide (CO2 ) and nitrogen (N2) for the process of upgrading the coal.As CO2 is a better solvent for non-polar compounds, the impuritiespresent in the coal (e.g. Sulfur based) that are non-polar in nature arebetter removed with CO2 rather than steam. Use of hot N2 mainly todecrease the moisture content in the coal improves the combustionperformances of the coal and hence the efficiency of the process. As aresult of this upgrading process, a higher heating value coal with lowerimpurities can be obtained.

One aspect of the disclosed processes is directed to an integrated coalupgrading and combustion process including the following steps. Air isseparated into streams of oxygen-enriched air and nitrogen-enriched air.The nitrogen-enriched air stream is heated. The heated nitrogen-enrichedair stream is introduced into a coal upgrading apparatus containingcoal. The heated nitrogen-enriched air is allowed to contact the coal inthe coal upgrading apparatus for a selected period of time. The streamof oxygen-enriched air and the coal from the coal upgrading apparatusare introduced to a combustion chamber. The coal and oxygen-enriched airare combusted in the combustion chamber thereby producing flue gas. Theflue gas is dried, purified, and compressed to produce a carbondioxide-rich fluid. The carbon dioxide-rich fluid is introduced to thecoal upgrading apparatus. The carbon dioxide-rich fluid is allowed tocontact the coal in the coal upgrading apparatus for a selected periodof time.

One aspect of the system is directed to an integrated coal upgrading andcombustion system that includes the following: a) an air separation unithaving an oxygen-enriched gas stream outlet and a nitrogen-enriched gasstream outlet; b) a heating device operably associated with thenitrogen-enriched air stream outlet; c) a coal upgrading apparatusoperatively associated with the heating device via a nitrogen feed line,the apparatus containing coal; d) a combustion chamber fluidlycommunicating with the oxygen-enriched air stream outlet, the combustionchamber having a flue gas outlet and being configured and adapted tocombust coal from the coal upgrading apparatus and oxygen-enriched gasfrom the air separation unit; e) a flue gas drying, purifying, andcompressing device fluidly communicating with the flue gas outlet; andf) a carbon dioxide-rich fluid feed line, wherein:

i) the drying, purifying, and compressing device is configured andadapted to dry, purify, and compress flue gas received from the flue gasoutlet to produce a carbon dioxide-rich fluid, and

ii) the drying, purifying, and compressing device fluidly communicateswith the coal upgrading apparatus via the carbon dioxide-rich fluid feedline.

Another aspect of the disclosed processes is directed to a process ofupgrading coal with heated nitrogen that includes the following steps. Anitrogen-containing gas having a nitrogen concentration greater thanthat of air is heated. The heated nitrogen-containing gas is allowed tocontact coal in a coal upgrading apparatus for a selected period oftime. The heated nitrogen-containing gas is allowed to be vented fromthe coal upgrading apparatus thereby removing at least some moisturefrom the coal and S and N bearing compounds.

Another aspect of the disclosed processes is directed to a process ofupgrading coal with carbon dioxide, including the following steps. Acarbon dioxide-containing fluid having a carbon dioxide concentrationgreater than that of air is provided. The carbon dioxide-containingfluid to contact coal in a coal upgrading apparatus for a period oftime, wherein the coal is not in a water slurry. The carbondioxide-containing fluid is allowed to be vented from the coal upgradingapparatus thereby removing at least some non-polar constituents from thecoal.

The disclosed processes can also include one or more of the followingaspects.

Collecting some of the flue gas from the combustion chamber before saiddrying, purifying, and compressing step is performed and combining thecollected flue gas with the stream oxygen-enriched gas being introducedto the combustion chamber.

Allowing the carbon dioxide-rich fluid to exit the coal upgradingapparatus and into a first cleaning unit, wherein contact between thecarbon dioxide-rich fluid and the coal in the coal upgrading apparatusresults in solvation of some non-polar constituents of the coal into thecarbon dioxide-rich fluid; and separating out some of the carbon dioxidefrom the combined carbon dioxide-rich fluid and the non-polarconstituents at the first cleaning unit; and introducing the separatedout carbon dioxide back into the coal upgrading apparatus; and removingat least some of a volatile component content of the non-polarconstituents from non-polar constituents; and introducing the separatedvolatile content into the combustion chamber.

During the step of allowing the carbon dioxide-rich fluid to contact,the coal upgrading apparatus is sealed and has a pressure greater thanambient.

The carbon dioxide-rich fluid is a liquid.

The carbon dioxide-rich fluid is a gas.

The carbon dioxide-rich fluid has a pressure of no less than 1,000 psia.

Allowing the nitrogen-enriched air to exit the coal upgrading apparatusand into a second cleaning unit, wherein contact between thenitrogen-enriched air and the coal in the coal upgrading apparatusresults in removal of some of the moisture in the coal; and separatingout moisture from the nitrogen-enriched air at the second cleaning unitto produce dried nitrogen-enriched air; and introducing the driednitrogen-enriched air into the coal upgrading apparatus.

During the step of allowing the heated nitrogen-enriched air to contact,the coal upgrading apparatus is vented.

The stream of nitrogen-enriched air is heated with heat produced by thecombusting step.

The stream of nitrogen-enriched air is heated with heat produced by aflame separate from said combusting step.

The stream of nitrogen-enriched air is heated to a temperature ofgreater than 100° C.

The oxygen-enriched gas has an oxygen concentration in a range of from21% to 99.5%.

The nitrogen-enriched gas has a nitrogen concentration in a range offrom 79% to 99.5%.

The coal is not in a slurry with water.

The combustion chamber is part of a boiler.

The disclosed integrated system can include one or more of the followingaspects.

The integrated system also includes an oxidant line adapted andconfigured to facilitate fluid communication between the oxygen-enrichedgas stream outlet and the combustion chamber; and a flue gas recycleline fluidly communicating with the drying, purifying, and compressingdevice and the oxidant line; and a mixing element disposed at a locationwherein the flue gas recycle line and the oxidant line fluidlycommunicate, the mixing element adapted and configured to mix flue gasreceived from the flue gas recycle line with oxidant from saidoxygen-enriched gas stream outlet.

The integrated system also includes a first cleaning unit fluidlycommunicating with the coal upgrading apparatus via a carbon dioxidevent line and via the carbon dioxide-rich fluid feed line, said firstcleaning unit also fluidly communicating with the combustion chamber viaa volatiles line, wherein the first cleaning unit is configured andadapted to: receive carbon dioxide-rich fluid from said coal upgradingapparatus containing a mixture of carbon dioxide and non-polarconstituents therefrom; and separate at least some of carbon dioxidefrom the mixture of carbon dioxide and non-polar constituents; anddirect the separated carbon dioxide to said coal upgrading apparatus viasaid carbon dioxide-rich fluid feed line; and separate out least some ofa volatile component content of the non-polar constituents from thenon-polar constituents; and direct the separated volatile componentcontent to said combustion chamber via said volatiles line.

The system also includes a second cleaning unit fluidly communicatingwith the coal upgrading unit via a nitrogen vent line and a nitrogenreturn line, wherein the first cleaning unit is configured and adaptedto: receive a mixture of nitrogen-enriched air and moisture from saidcoal upgrading apparatus via said nitrogen vent line; separate at leastsome moisture from the mixture of nitrogen-enriched air and moisture toproduce dried nitrogen-enriched air; and direct the driednitrogen-enriched air into said coal upgrading apparatus.

The system also includes a heat exchanger adapted and configured to heatnitrogen-enriched air from The system also includes a nitrogen-enrichedair stream outlet with heat produced from combustion of coal andoxygen-enriched air in The system also includes combustion chamber.

As best illustrated in FIG. 1, air feed 5 is separated intooxygen-enriched air and nitrogen-enriched air at air separation unit(ASU) 7. The oxygen-enriched air leaves oxygen-enriched air outlet 8 andis directed by oxidant line 10 to combustion chamber 15. Thenitrogen-enriched air leaves nitrogen-enriched air outlet 6 and isdirected to heating device 14 and then to coal upgrading apparatus 3.Typical oxygen and nitrogen concentrations are in a range of from 80% to99.5%. Coal from coal supply 1 is also caused to be placed into coalupgrading apparatus 3.

Coal and oxygen-enriched air are combusted in combustion chamber 15thereby producing flue gas. Optionally, air may also be fed to thecombustion chamber. In this case, the total oxygen concentration of thecombined oxygen-enriched air and air entering the combustion chamber 15is 21% by volume or higher. The system and process is particularlyapplicable to a combustion chamber 15 that is a boiler. The flue gas isdirected to optional flue gas cleaning unit 13 to remove impurities in aknown way. The non-cleaned flue gas or cleaned flue gas (in the casewhere unit 13 is selected) is then directed to flue gas drying,purifying, and compressing device 17. Cleaned, dried, purified (asrequired), and compressed flue gas is then directed to coal upgradingapparatus 3 via carbon dioxide-rich fluid feed line 20. Optionally,cleaned, dried, purified, and compressed flue gas may also be directedout of the drying, purifying, and compressing device to a use or storagedevice 19.

In operation, coal is alternately upgraded by either thenitrogen-enriched air or the carbon dioxide-rich fluid.

During treatment by the nitrogen-enriched air, the nitrogen-enriched airis heated at heating device. While the heating device may be external tothe combustion chamber 15 and combustion process operated therein,preferably heat is imparted by the combustion process to thenitrogen-enriched air via heating device 15. The system and process aremore fully integrated in this manner thereby reducing operating andcapital costs. The temperature of the nitrogen is chosen so that adesired level of moisture can be removed with minimal or no release ofvolatiles from the coal. These volatiles are preferably retained by thecoal from a combustion point of view. The nitrogen also may remove somesulfur-containing compounds and nitrogen-containing compounds. Removingthe moisture from the coal improves the combustion characteristics asthe heating value of the coal (Btu/weight basis) will be increased. Inother words, a lower amount of the dried coal will be required toproduce the same energy by combustion as the undried coal. One skilledin the art will appreciate that higher temperatures will increase theefficiency by which moisture is removed from the coal. The heatednitrogen-enriched air carries away some of the moisture via vent line 2.While the coal upgrading apparatus 3 may be sealed and optionallypressurized during treatment of the coal by the nitrogen-enriched air,preferably it is at least partially vented during treatment.

During treatment by the carbon dioxide-rich fluid, the coal upgradingapparatus 3 is pressurized with the carbon dioxide-rich fluid fromcarbon dioxide-rich fluid feed line 20 and then sealed. The pressurizedcarbon dioxide-rich fluid is then allowed to contact the coal for adesired period of time in order to dissolve non-polar constituents (suchas sulfur-containing compounds and nitrogen-containing compounds) in thecoal. The pressurized carbon-dioxide can also dissolve heavy metals,non-limiting examples of which include Arsenic and Sodium. At relativelyhigher pressures, carbon dioxide exhibits excellent solvent properties.The carbon dioxide-rich fluid may be introduced as a gas or a liquid.While the carbon dioxide-rich fluid will often include multiplecomponents, including carbon dioxide, oxygen, nitrogen, and NOx, thecarbon dioxide-rich fluid may potentially also be in a supercriticalfluid state. One skilled in the art will appreciate that the pressureand temperature of the carbon dioxide-rich fluid may be selected basedupon the type of coal and impurities targeted. Preferably, the carbondioxide-rich fluid has a pressure of no less than 1000 psia. Aftertreatment, the coal upgrading apparatus is vented via a carbon dioxidevent line 4. It should be noted that a single line may be used for vents2 and 4.

As best shown in FIG. 2, carbon dioxide exiting the coal upgradingapparatus 3 may optionally be cleaned and recycled. In this embodiment,carbon dioxide containing non-polar constituents from the coal exitscoal upgrading apparatus 3 via carbon dioxide vent line 4 and isintroduced to first cleaning unit 11. At least some of the carbondioxide is then separated from the non-polar constituents in a knownmanner. The separated carbon dioxide is then directed to carbondioxide-rich fluid feed line 20 for reentry into coal upgradingapparatus 3. At least some of the volatile content of the non-polarconstituents is then separated out and directed to the combustionchamber 15 via volatiles line 18 where they are combusted with theoxygen-enriched air and coal. The remainder of the carbondioxide-depleted and volatile-depleted content, such as heavy metals,may be vented via vent 22.

As best illustrated in FIG. 3, the nitrogen exiting the coal upgradingapparatus 3 may optionally be cleaned and recycled. Nitrogen andmoisture exiting the coal upgrading apparatus 3 via nitrogen vent 2 maybe dried at second cleaning unit 9 and the dried nitrogen recycled backto the coal upgrading apparatus 3.

As best shown in FIG. 4, the nitrogen and carbon dioxide leaving thecoal upgrading apparatus 3 may optionally be cleaned and recycled asdescribed above in the embodiments of FIGS. 2 and 3.

As best illustrated in FIG. 5, a portion of flue gas may be recycled tothe combustion chamber 15. After the flue gas is cleaned at optionalflue gas cleaning unit 13, a portion the cleaned flue gas then may bedirected by flue gas recycle line 24 to mixer 12 where it is mixed withoxygen-enriched gas and introduced to combustion chamber 15 via oxidantline 10.

As best shown in FIG. 6, the carbon dioxide exiting the coal upgradingapparatus 3 may be cleaned and a portion of the flue gas may be recycledto the combustion chamber 15 as described above in the embodiments ofFIGS. 2 and 5.

As best shown in FIG. 7, the nitrogen exiting the coal upgradingapparatus 3 may be cleaned and a portion of the flue gas may be recycledto the combustion chamber 15 as described above in the embodiments ofFIGS. 3 and 5.

As best shown in FIG. 8, the carbon dioxide and nitrogen exiting thecoal upgrading apparatus 3 may be cleaned and a portion of the flue gasmay be recycled to the combustion chamber 15 as described above in theembodiments of FIGS. 4 and 5.

The method and system need not be integrated with a combustionprocess/system nor require treatment by both carbon dioxide-rich fluidand nitrogen-enriched air. Indeed, coal may be upgraded by carbondioxide-rich fluid alone or by nitrogen-enriched air alone and apartfrom a combustion process/system.

As best illustrated in FIG. 9, coal may be upgraded by carbon dioxidewithout nitrogen. Carbon dioxide-rich fluid from any source is directedto coal upgrading apparatus 3 via carbon dioxide-rich fluid feed 20. Inthis case, the carbon dioxide-rich fluid need not be derived from fluegas. During treatment by the carbon dioxide-rich fluid, the coalupgrading apparatus 3 is pressurized with the carbon dioxide-rich fluidfrom carbon dioxide-rich fluid feed line 20 and then sealed. Thepressurized carbon dioxide-rich fluid is then allowed to contact thecoal for a desired period of time in order to solvate non-polarconstituents in the coal. At relatively higher temperatures andpressures, carbon dioxide exhibits excellent solvent properties. Thecarbon dioxide-rich fluid may be introduced as a gas or a liquid. Whilethe carbon dioxide-rich fluid will often include multiple components,including carbon dioxide, oxygen, nitrogen, and NOx, the carbondioxide-rich fluid may potentially also be in a supercritical fluidstate. One skilled in the art will appreciate that the pressure andtemperature of the carbon dioxide-rich fluid may be selected based uponthe type of coal and impurities targeted. Preferably, the carbondioxide-rich fluid has a pressure of no less than 1000 psia. Aftertreatment, the coal upgrading apparatus is vented via a carbon dioxidevent line 4.

As best shown in FIG. 10, the embodiment of FIG. 9 may include carbondioxide cleaning. In this embodiment, carbon dioxide containingnon-polar constituents from the coal exits coal upgrading apparatus 3via carbon dioxide vent line 4 and is introduced to first cleaning unit11. At least some of the carbon dioxide is then separated from thenon-polar constituents in a known manner. The separated carbon dioxideis then either directed to carbon dioxide-rich fluid feed line 20 foruse or to vent 22 for use and/or storage.

As best illustrated in FIG. 11, the embodiment of FIG. 9 may beintegrated with a combustion process/system. The integrated nature ofthe coal upgrading and combustion of coal and oxygen-enriched air lowersboth operating and capital costs. Air feed 5 is separated intooxygen-enriched air and nitrogen-enriched air at air separation unit(ASU) 7. The oxygen-enriched air leaves oxygen-enriched air outlet 8 andis directed by oxidant line 10 to combustion chamber 15. Thenitrogen-enriched air leaves nitrogen-enriched air outlet 6 and isdirected to heating device 14 and then to coal upgrading apparatus 3.Typical oxygen and nitrogen concentrations are in a range of from 80% to99.5% by volume. Coal from coal supply 1 is also caused to be placedinto coal upgrading apparatus 3.

Coal and oxygen-enriched air are combusted in combustion chamber 15thereby producing flue gas. Optionally, air may also be fed to thecombustion chamber. In this case, the total oxygen concentration of thecombined oxygen-enriched air and air entering the combustion chamber 15is 21% or higher. The system and process is particularly applicable to acombustion chamber 15 that is a boiler. The flue gas is directed tooptional flue gas cleaning unit 13 to remove impurities in a known way.The non-cleaned flue gas or cleaned flue gas (in the case where unit 13is selected) is then directed to flue gas drying, purifying, andcompressing device 17. Cleaned, dried, purified, and compressed flue gasis then directed to coal upgrading apparatus 3 via carbon dioxide-richfluid feed line 20. Optionally, cleaned, dried, purified, and compressedflue gas may also be directed out of the drying, purifying, andcompressing device to a use or storage device 19.

As best shown in FIG. 12, the embodiment of FIG. 11 may also includecarbon dioxide cleaning. In this embodiment, carbon dioxide containingnon-polar constituents from the coal exits coal upgrading apparatus 3via carbon dioxide vent line 4 and is introduced to first cleaning unit11. At least some of the carbon dioxide is then separated from thenon-polar constituents in a known manner. The separated carbon dioxideis then directed to carbon dioxide-rich fluid feed line 20 for reentryinto coal upgrading apparatus 3. At least some of the volatile contentof the non-polar constituents is then separated out and directed to thecombustion chamber 15 via volatiles line 18 where they are combustedwith the oxygen-enriched air and coal. The remainder of the carbondioxide-depleted and volatile-depleted content, such as heavy metals,may be vented via vent 22.

As best shown in FIG. 13, the embodiment of FIG. 11 may also includeflue gas recycling. After the flue gas is cleaned at optional flue gascleaning unit 13, a portion the cleaned flue gas then may be directed byflue gas recycle line 24 to mixer 12 where it is mixed withoxygen-enriched gas and introduced to combustion chamber 15 via oxidantline 10.

As best illustrated in FIG. 14, the embodiment of FIG. 12 may alsoinclude flue gas recycling. After the flue gas is cleaned at optionalflue gas cleaning unit 13, a portion the cleaned flue gas then may bedirected by flue gas recycle line 24 to mixer 12 where it is mixed withoxygen-enriched gas and introduced to combustion chamber 15 via oxidantline 10.

As best shown in FIG. 15, the coal may be upgraded in coal upgradingapparatus 3 with nitrogen without carbon dioxide. Nitrogen ornitrogen-enriched air from any source is directed to heating device 14and then to coal upgrading apparatus 3. Typical nitrogen concentrationsfor use in this embodiment are in a range of from 80% to 99.5%. Duringtreatment by the nitrogen-enriched air, the nitrogen-enriched air isheated at heating device. The temperature of the nitrogen is chosen sothat a desired level of moisture can be removed with minimal or norelease of volatiles from the coal. These volatiles are preferablyretained by the coal from a combustion point of view. The heatednitrogen also may remove some sulfur-containing compounds andnitrogen-containing compounds. Removing the moisture from the coalimproves the combustion characteristics as the heating value of the coal(Btu/weight basis) will be increased. In other words, a lower amount ofthe dried coal will be required to produce the same energy by combustionas the undried coal. One skilled in the art will appreciate that highertemperatures will increase the efficiency by which moisture is removedfrom the coal. The heated nitrogen-enriched air carries away some of themoisture via vent line 2. While the coal upgrading apparatus 3 may besealed and optionally pressurized during treatment of the coal by thenitrogen-enriched air, preferably it is at least partially vented duringtreatment.

As best illustrated in FIG. 16, the embodiment of FIG. 15 may includenitrogen cleaning and recycling. Nitrogen and moisture exiting the coalupgrading apparatus 3 via nitrogen vent 2 may be dried at secondcleaning unit 9 and the dried nitrogen recycled back to the coalupgrading apparatus 3.

As best shown in FIG. 17, the embodiment of FIG. 15 may be integratedwith an air separation unit (ASU). Air feed 5 is separated intooxygen-enriched air and nitrogen-enriched air at air separation unit 7.The oxygen-enriched air leaves oxygen-enriched air outlet 8 and isdirected by oxidant line 10 to combustion chamber 15. Thenitrogen-enriched air leaves nitrogen-enriched air outlet 6 and isdirected to heating device 14 and then to coal upgrading apparatus 3.Typical nitrogen concentrations for use in this embodiment are in arange of from 80% to 99.5%. Typical nitrogen concentrations innitrogen-enriched air from an ASU are in a range of from 80% to 99.5%.

As best illustrated in FIG. 18, the embodiment of FIG. 17 may includenitrogen cleaning and recycling. Nitrogen and moisture exiting the coalupgrading apparatus 3 via nitrogen vent 2 may be dried at secondcleaning unit 9 and the dried nitrogen recycled back to the coalupgrading apparatus 3.

Preferred processes and apparatus for practicing the present inventionhave been described. It will be understood and readily apparent to theskilled artisan that many changes and modifications may be made to theabove-described embodiments without departing from the spirit and thescope of the present method. The foregoing is illustrative only and thatother embodiments of the integrated processes and apparatus may beemployed without departing from the true scope of the invention whoseaspects are described in the following claims.

1. A process of upgrading coal with carbon dioxide, comprising the stepsof: providing a carbon dioxide-containing fluid having a carbon dioxideconcentration greater than that of air; allowing the carbondioxide-containing fluid to contact coal in a coal upgrading apparatusfor a period of time, wherein the coal is not in a water slurry; andallowing the carbon dioxide-containing fluid to be vented from the coalupgrading apparatus thereby removing at least some non-polarconstituents from the coal.
 2. The process of claim 1, wherein the coalupgrading apparatus is at a pressure greater than ambient and is sealedduring contact of the carbon dioxide-containing fluid and coal.
 3. Theprocess of claim 1, wherein the coal is not in a slurry with water. 4.The process of claim 1, further comprising the steps of: separating airinto streams of oxygen-enriched air and nitrogen-enriched air;introducing the stream of oxygen-enriched air and the coal from the coalupgrading apparatus to a combustion chamber; combusting the coal andoxygen-enriched air in the combustion chamber thereby producing fluegas; and drying, purifying, and compressing the flue gas to produce thecarbon dioxide-containing fluid.
 5. The process of claim 1, furthercomprising the steps of: collecting some of the flue gas from thecombustion chamber before said drying, purifying, and compressing stepis performed; and combining the collected flue gas with the streamoxygen-enriched gas being introduced to the combustion chamber.
 6. Theprocess of claim 5, further comprising the steps of: allowing the carbondioxide-containing fluid to exit the coal upgrading apparatus and into afirst cleaning unit, wherein contact between the carbondioxide-containing fluid and the coal in the coal upgrading apparatusresults in dissolution of some non-polar constituents of the coal intothe carbon dioxide-containing fluid; separating out some of the carbondioxide from the combined carbon dioxide-containing fluid and thenon-polar constituents at the first cleaning unit; introducing theseparated out carbon dioxide back into the coal upgrading apparatus;removing at least some of a volatile component content of the non-polarconstituents from non-polar constituents; and introducing the separatedvolatile content into the combustion chamber.
 7. The process of claim 1,wherein the carbon dioxide-containing fluid is a liquid.
 8. The processof claim 1, wherein the carbon dioxide-containing fluid is a gas.
 9. Theprocess of claim 1, wherein the carbon dioxide-containing fluid has apressure of no less than 1,000 psia.
 10. The process of claim 1, furthercomprising the steps of: heating a nitrogen-enriched air stream;introducing the heated nitrogen-enriched air stream into a coalupgrading apparatus containing coal; and allowing the heatednitrogen-enriched air to contact the coal in the coal upgradingapparatus for a selected period of time.
 11. The process of claim 10,further comprising the steps of: allowing the nitrogen-enriched air toexit the coal upgrading apparatus and into a second cleaning unit,wherein contact between the nitrogen-enriched air and the coal in thecoal upgrading apparatus results in removal of some of the moisture inthe coal; separating out moisture from the nitrogen-enriched air at thesecond cleaning unit to produce dried nitrogen-enriched air; andintroducing the dried nitrogen-enriched air into the coal upgradingapparatus.
 12. The process of claim 1, wherein, during said step ofallowing the heated nitrogen-enriched air to contact, the coal upgradingapparatus is vented.
 13. The process of claim 10, further comprising thesteps of: separating air into streams of oxygen-enriched air andnitrogen-enriched air; introducing the stream of oxygen-enriched air andthe coal from the coal upgrading apparatus to a combustion chamber; andcombusting the coal and oxygen-enriched air in the combustion, whereinthe stream of nitrogen-enriched air is heated with heat produced by saidcombusting step.
 14. The process of claim 4, wherein the oxygen-enrichedgas has an oxygen concentration in a range of from 21% to 99.5%.
 15. Theprocess of claim 4, wherein the combustion chamber is part of a boiler.